Adsorption of binary liquid mixtures on heterogeneous adsorbents with uniform energy distribution

Abstract

A simple analytic equation is derived to describe the surface excess isotherm for adsorption of binary liquid mixtures on heterogeneous adsorbents. The model assumes that the adsorbent heterogeneity can be described by a uniform distribution of the adsorbate selectivity and that the adsorbed phase is ideal. The parameters of the model are, m, the monolayer capacity of the adsorbent, and the mean (μ) and the variance (σ 2) of the distribution function. Experimental isotherms for adsorption of various hydrocarbon mixtures on silica gel and graphon are described by the model. A parametric study of the effects of μ. and σ on the shape of the surface excess isotherm is carried out to demonstrate the flexibility of the model. It is shown that the “S” shaped surface excess isotherm may be caused by the adsorbent surface heterogeneity even when the bulk liquid and the adsorbed phases are ideal.